Liquid crystal display device

ABSTRACT

A pair of electrodes which constitute an upper layer and a lower layer with respect to an interlayer insulation film are formed as different layers at respective pixel regions on a liquid-crystal-side surface of one substrate out of respective substrates which are arranged to face each other in an opposed manner by way of liquid crystal. At two pixel regions which are selected from the respective pixel regions, the height of background layers on which the electrodes which constitute the lower layers with respect to the interlayer insulation films are formed differs with respect to a surface of one substrate. The film thickness of the interlayer insulation film is set small with respect to the high background layer out of respective background layers which differ in height and is set large with respect to the low background layer out of respective background layers which differ in height.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of U.S. application Ser.No. 10/863,752 filed Jun. 9, 2004 now U.S. Pat. No. 6,995,818, which isa Divisional application of U.S. application Ser. No. 10/173,012 filedJun. 18, 2002 now U.S. Pat. No. 6,768,531. Priority is claimed based onU.S. application Ser. No. 10/863,752 filed Jun. 9, 2004, which claimspriority to U.S. application Ser. No. 10/173,012 filed Jun. 18, 2002,which claims priority to Japanese Patent Application No. 2001-231333filed on Jul. 31, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device, andmore particularly to a so-called lateral electric field type liquidcrystal display device.

2. Description of the Related Art

In a so-called lateral electric field type liquid crystal displaydevice, on each pixel region on a liquid-crystal-side surface of onesubstrate out of respective substrates which are arranged to face eachother in on opposed manner by way of liquid crystal, a pixel electrodeand a counter electrode which generates an electric field between thepixel electrode and the counter electrode are formed, and the lighttransmittance of the liquid crystal is controlled by components of theelectric field substantially parallel to the substrates.

In such a liquid crystal display device adapted to an active matrixtype, on the liquid-crystal-side surface of the above-mentioned onesubstrate, regions which are surrounded by gate signal lines which areextended in the x direction and are arranged in parallel in the ydirection and the drain signal lines which are extended in the ydirection and are arranged in parallel in the x direction are formed aspixel regions, and a switching element which is operated in response toscanning signals from the gate line, a pixel electrode to which videosignals are supplied from the drain signal lines through the switchingelement and a counter electrode which is arranged in a spaced-apartmanner from the pixel electrode are formed on each pixel region.

Then, in performing the color display, there has been known a liquidcrystal display device having the structure in which color filters areformed on the above-mentioned one substrate side and the color filtersare not formed on the other substrate side. Such a structure is devisedto reduce the influence of the displacement of alignment of the othersubstrate to one substrate to cope with the recent demand for highdefinition.

SUMMARY OF INVENTION

However, in the liquid crystal display device having such aconstitution, the layer thickness is not made uniform over all colorfilters of red (R), green (G) and blue (B).

Such a situation occurs when the layer thickness of respective colorfilters are intentionally set to different values to attain the balanceof transmittance or color purity among respective color filters of R, Gand B or when the layer thickness is not made uniform over all colorfilters of red (R), green (G) and blue (B) due to the irregularities inmanufacturing the color filters.

In these cases, when the pixel electrodes and the counter electrodes areformed by way of an interlayer insulation film on upper layers of thecolor filters, the height of the interlayer insulation film with respectto a surface of one substrate is reflected on the layer thickness of thecolor filters so that the respective heights of the pixel electrodes orthe counter electrodes (heights from the surface of one substrate)differ.

This makes the layer thickness of the liquid crystal at respectivepixels non-uniform so that the equal light transmittance cannot beobtained with respect to the respective color pixels.

Further, when the interlayer insulation film which is interposed betweenthe pixel electrodes and the counter electrodes is made of resinmaterial or the like which is formed by coating, the thickness of theinterlayer insulation film differs depending on the respective pixels ofdifferent colors. Accordingly, the voltage drop which differs dependingon the interlayer insulation film between the pixel electrodes and thecounter electrodes displaces brightness-voltage characteristics thusleading to the collapsing of the color balance of the intermediate grayscale.

The present invention has been made in view of these circumstances andit is an object of the present invention to provide a liquid crystaldisplay device which can enhance the display quality.

To briefly explain the summary of the typical inventions among theinventions disclosed in this specification, they are as follows.

Means 1.

A liquid crystal display device according to the present invention is,for example, characterized in that:

a pair of electrodes which constitute an upper layer and a lower layerwith respect to an interlayer insulation film are formed as differentlayers at respective pixel regions on a liquid-crystal-side surface ofone substrate out of respective substrates which are arranged to faceeach other in an opposed manner by way of liquid crystal,

at two pixel regions which are selected from the respective pixelregions, the heights of background layers on which the electrodes whichconstitute the lower layers with respect to the interlayer insulationfilms differ with respect to a surface of one substrate, and

the film thickness of the interlayer insulation film is set small withrespect to the high background layer out of the respective backgroundlayers which differ in height and is set large with respect to the lowbackground layer out of the respective background layers.

Means 2.

A liquid crystal display device according to the present invention is,for example, characterized in that:

a pair of electrodes which constitute an upper layer and

a lower layer with respect to an interlayer insulation film are formedon at least color filters as different layers at respective pixelregions on a liquid-crystal-side surface of one substrate out ofrespective substrates which are arranged to face each other in anopposed manner by way of liquid crystal from the one substrate side,

at two pixel regions which are selected from the respective pixelregions and on which two color filters of different colors are formed,the heights of surfaces of the color filters differ with respect to asurface of one substrate, and

the film thickness of the interlayer insulation film is set to satisfy afollowing formula (1).0<film thickness difference of the interlayer insulation film betweenpixel regions<film thickness difference of the color filters betweenpixel regions  (1)Means 3.

A liquid crystal display device according to the present invention is,for example, characterized in that:

a pair of electrodes which constitute an upper layer and a lower layerwith respect to an interlayer insulation film are formed on at leastcolor filters as different layers at respective pixel regions on aliquid-crystal-side surface of one substrate out of respectivesubstrates which are arranged to face each other in an opposed manner byway of liquid crystal from the one substrate side,

at two pixel regions which are selected from the respective pixelregions and on which two color filters of different colors are formed,the heights of surfaces of the color filters differ with respect to asurface of one substrate, and the film thickness of the interlayerinsulation film is set to satisfy a following formula (2).¼×film thickness difference of color filter between pixel regions<filmthickness difference of interlayer insulation film between pixelregions, <¾×film thickness difference of color filter between pixelregions  (2)Means 4.

A liquid crystal display device according to the present invention is,for example, based on the constitution of the means 2 or 3,characterized in that the film thickness of the interlayer insulationfilm is set to satisfy a following formula (3).film thickness of interlayer insulation film< 3/2 times film thicknessof thickest color filter  (3)Means 5.

A liquid crystal display device according to the present invention is,for example, based on the constitution of the means 2 or 3,characterized in that the film thickness of the interlayer insulationfilm is set to satisfy a following formula (4).¼ times film thickness of thinnest color filter<film thickness ofinterlayer insulation film< 3/2 times film thickness of thickest colorfilter  (4)Means 6.

A liquid crystal display device according to the present invention is,for example, characterized in that:

a pair of electrodes which constitute an upper layer and a lower layerwith respect to an interlayer insulation film are formed as differentlayers at respective pixel regions on a liquid-crystal-side surface ofone substrate out of respective substrates which are arranged to faceeach other in an opposed manner by way of liquid crystal,

at the respective pixel regions, the heights of background layers onwhich the electrodes which constitute the lower layers with respect tothe interlayer insulation films are formed differ with respect to asurface of one substrate, and

the film thickness of the interlayer insulation film is set small withrespect to the high background layer out of the respective backgroundlayers which differ in height and is set large with respect to the lowbackground layer out of the respective background layers which differ inheight.

Means 7.

A liquid crystal display device according to the present invention is,for example, characterized in that:

at respective pixel regions on a liquid-crystal-side surface of onesubstrate out of respective substrates which are arranged to face eachother in an opposed manner by way of liquid crystal,

a pair of electrodes are formed by way of a protective film which isformed by sequentially laminating a first protective film and a secondprotective film,

the respective electrodes are arranged in a spaced-apart manner in aplan view so as to generate an electric field between the electrodes,

the relationship between the film thicknesses d₃, d₂ of the firstprotective film and the second protective film on the electrode arrangedas a layer below the protective film and the film thicknesses d₃′, d₂′of the first protective film and the second protective film on a regionbetween the pair of electrodes satisfies a following formula (5)d ₃ ≈d ₃ ′, d ₂ <d ₂ ′<d ₂ +d ₄  (5), and

the relationship between the layer thickness d₁ of liquid crystal on theelectrode arranged below the protective film and the layer thickness d₁′of the liquid crystal on the region between the pair of electrodessatisfies a following formula (6).d₁ ≈d ₁′ (here, d₁≦d₁′)  (6)Means 8.

A liquid crystal display device according to the present invention is,for example, characterized in that:

at respective pixel regions formed on a liquid-crystal-side surface ofone substrate out of respective substrates which are arranged to faceeach other in an opposed manner by way of liquid crystal,

a pair of electrodes are formed by way of a protective film which isformed by sequentially laminating a first protective film and a secondprotective film,

the respective electrodes are arranged in a spaced-apart manner in aplan view so as to generate an electric field between the electrodes,and

in two selected pixel regions, assuming the film thickness of the firstprotective film in one pixel region as x₃, the film thickness of thesecond protective film in one pixel region as x₂, the film thickness ofthe first protective film in the other pixel region as y₃ and the filmthickness of the second protective film in the other pixel region as y₂,a following formula (7) is established.X ₂ +x ₃ y ₂ +y ₃ , x ₃ >y ₃ , x ₂ <y ₂  (7)

Further, when the distance from the substrate to the liquid crystallayer differs, the thickness of the liquid crystal layer differs. In thelateral electric field method, the driving voltage depends on thethickness of the liquid crystal layer. That is, the thicker the liquidcrystal layer, the same brightness can be obtained with the lowervoltage. On the other hand, this implies that a B-V curve differsbetween two pixels where the distance from the substrate to the liquidcrystal layer differs from each other and hence, the same gray scalecannot be displayed using the equal voltage. Followings are respectivelymeans which can solve such a drawback.

(Means 9)

A liquid crystal display device according to the present invention, forexample, comprises;

a liquid crystal layer which is sandwiched between a pair of substrateswhich face each other in an opposed manner,

a plurality of pixel regions, and

pixel electrodes and counter electrodes which are formed on each pixelregion on a liquid-crystal-layer-side surface of one substrate out ofthe pair of substrates, wherein

each pixel region includes a first pixel and a second pixel respectivelyhaving the plurality of counter electrodes formed thereon,

the distance from one substrate to the counter electrodes at the firstpixel is set longer than the distance at the second pixel, and

the distance between the plurality of counter electrodes in the pixel atthe first pixel is set shorter than the distance at the second pixel.

(Means 10)

A liquid crystal display device according to the present invention, forexample, comprises;

a liquid crystal layer which is sandwiched between a pair of substrateswhich face each other in an opposed manner,

a plurality of pixel regions, and

pixel electrodes and counter electrodes which are formed on each pixelregion on a liquid-crystal-layer-side surface of one substrate out ofthe pair of substrates, wherein

each pixel region includes a first pixel and a second pixel respectivelyhaving the plurality of pixel electrodes formed thereon,

the distance from one substrate to the pixel electrodes at the firstpixel is set longer than the distance at the second pixel, and

the distance between the plurality of pixel electrodes in the pixel atthe first pixel is set shorter than the distance at the second pixel.

(Means 11)

A liquid crystal display device according to the present invention, forexample, comprises;

a liquid crystal layer which is sandwiched between a pair of substrateswhich face each other in an opposed manner,

a plurality of pixel regions, and

pixel electrodes and counter electrodes which are formed on each pixelregion on a liquid-crystal-layer-side surface of one substrate out ofthe pair of substrates, wherein

each pixel region includes a first pixel and a second pixel which differin the distance from one substrate to the counter electrodes,

the distance from one substrate to the counter electrodes at the firstpixel is set longer than the distance at the second pixel, and

the distance between the pixel electrodes and the counter electrodes atthe first pixel is set shorter than the distance at the second pixel.

(Means 12)

A liquid crystal display device according to the present invention is,for example, based on the constitution of the means 11, characterized inthat the pixel electrodes and the counter electrodes are constituted asseparate layers.

(Means 13)

A liquid crystal display device according to the present invention is,for example, based on the constitution of the means 11, characterized inthat the pixel electrodes and the counter electrodes are constituted asthe same layer.

(Means 14)

A liquid crystal display device according to the present invention is,for example, based on the constitution of the means 9, characterized inthat the counter electrodes are formed on an organic film.

(Means 15)

A liquid crystal display device according to the present invention is,for example, based on means 10, characterized in that the pixelelectrodes are formed on an organic film.

(Means 16)

A liquid crystal display device according to the present invention is,for example, based on the constitution of the means 13, characterized inthat the pixel electrodes and the counter electrodes are formed on anorganic film.

(Means 17)

A liquid crystal display device according to the present invention, forexample, comprises;

a liquid crystal layer which is sandwiched between a pair of substrateswhich face each other in an opposed manner,

a plurality of pixel regions, and

pixel electrodes and counter electrodes which are formed on each pixelregion on a liquid-crystal-layer-side surface of one substrate out ofthe pair of substrates, wherein

each pixel region includes a first pixel and a second pixel which differin the difference between the distance between one substrate and thepixel electrodes and the distance between one substrate and the counterelectrodes,

the difference at the first pixel is smaller than the difference at thesecond pixel,

the distance between one substrate and the pixel electrodes at the firstpixel is larger than the distance between one substrate and the pixelelectrodes at the second pixel, and

the distance between one substrate and the counter electrodes at thefirst pixel is larger than the distance between one substrate and thecounter electrodes at the second pixel.

(Means 18)

A liquid crystal display device according to the present invention is,for example, based on the constitution of the means 17, characterized inthat the pixel electrodes and the counter electrodes are formed asdifferent layers by way of an organic film.

(Means 19)

A liquid crystal display device according to the present invention is,for example, based on the constitution of any one of the means 14 to 16or 18, characterized in that the organic film is constituted of colorfilters.

(Means 20)

A liquid crystal display device according to the present invention is,for example, based on the constitution of any one of the means 9 to 11or 17, characterized in that the first pixel and the second pixel arearranged close to each other.

Further means according to the present invention will become apparentfrom the description of this specification and attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing one embodiment of a liquidcrystal display device according to the present invention.

FIG. 2 is an overall equivalent circuit diagram showing one embodimentof the liquid crystal display device according to the present invention.

FIG. 3 is a plan view showing one embodiment of a pixel of the liquidcrystal display device according to the present invention.

FIG. 4 is a cross-sectional view taken along a line IV—IV shown in FIG.3.

FIG. 5 is a cross-sectional view of another embodiment of the liquidcrystal display device according to the present invention.

FIG. 6 is a cross-sectional view of another embodiment of the liquidcrystal display device according to the present invention.

FIG. 7 is a cross-sectional view of another embodiment of the liquidcrystal display device according to the present invention.

FIG. 8 is a cross-sectional view of another embodiment of the liquidcrystal display device according to the present invention.

FIG. 9 is a cross-sectional view of another embodiment of the liquidcrystal display device according to the present invention.

FIG. 10 is a cross-sectional view of another embodiment of the liquidcrystal display device according to the present invention.

FIG. 11 is a plan view of another embodiment of the pixel of the liquidcrystal display device according to the present invention.

FIG. 12 is a cross-sectional view taken along a line XII—XII shown inFIG. 11.

FIG. 13 is an explanatory view for explaining an advantageous effectaccording to the present invention.

FIG. 14 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the present invention.

FIG. 15 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the present invention.

FIG. 16 is an explanatory view necessary for showing portions ofrespective pixels shown in FIG. 14 and FIG. 15.

FIG. 17 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the present invention.

FIG. 18 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the present invention.

FIG. 19 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the present invention.

FIG. 20 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the present invention.

FIG. 21 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the present invention.

FIG. 22 is a cross-sectional view showing another embodiment of theliquid crystal display device according to the present invention.

FIG. 23 is an explanatory view showing the displacement of a B-V curve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of a liquid crystal device according to thepresent invention are explained hereinafter in conjunction with attacheddrawings.

Embodiment 1

<Equivalent Circuit>

FIG. 2 is an overall equivalent circuit diagram showing one embodimentof a liquid crystal display device according to the present invention.Although the drawing shows the equivalent circuit, it is depictedcorresponding to an actual geometrical arrangement.

In FIG. 2, a pair of transparent substrates SUB1, SUB2 which arearranged to face each other in an opposed manner by way of liquidcrystal are provided. The liquid crystal is sealed by a sealing memberSL which is also served for fixing the other transparent substrate SUB2to one transparent substrate SUB1.

On a liquid-crystal-side surface of the above-mentioned one transparentsubstrate SUB1 which is surrounded by the sealing member SL, gate signallines GL which are extended in the x direction and are arranged inparallel in the y direction and drain signal lines DL which are extendedin the y direction and are arranged in parallel in the x direction areformed.

Regions which are surrounded by respective gate signal lines GL andrespective drain signal lined DL constitute pixel regions and a mass ofthese respective pixel regions in a matrix array constitutes a liquidcrystal display part AR.

Common counter voltage signal lines CL which run in the inside ofrespective pixel regions are formed on respective pixel regions whichare arranged in parallel in the x direction. These counter voltagesignal lines CL constitute signal lines for supplying signal voltageswhich become the reference with respect to video signals to counterelectrodes CT of respective pixel regions which will be explained later.

On each pixel region, a thin film transistor TFT which is operated inresponse to scanning signals from one-side gate signal line GL and apixel electrode PX to which the video signals are supplied from theone-side drain signal line DL through the thin film transistor TFT areformed.

The pixel electrode PX generates an electric field between the pixelelectrode PX and the counter electrode CT which is connected to thecounter voltage signal line CL and the light transmittance of the liquidcrystal is controlled based on the electric field.

Respective ends of the gate signal lines GL are extended over thesealing member SL and the extended ends constitute terminals to whichoutput terminals of a vertical scanning driving circuit V are connected.Further, to input terminals of the vertical scanning driving circuit V,signals from a printed circuit board which is arranged outside a liquidcrystal display panel are inputted.

The vertical scanning driving circuit V is constituted of a plurality ofsemiconductor devices, wherein a plurality of gate signal lines GL whichare arranged close to each other are formed into a group and onesemiconductor device is allocated to every group.

In the same manner, respective ends of the drain signal lines DL areextended over the sealing member SL and the extended ends constituteterminals to which output terminals of a video signal driving circuit Heare connected. Further, to input terminals of the video signal drivingcircuit He, signals from the printed circuit board which is arrangedoutside the liquid crystal display panel are inputted.

The video signal driving circuit He is also constituted of a pluralityof semiconductor devices, wherein a plurality of drain signal lines DLwhich are arranged close to each other are formed into a group and onesemiconductor device is allocated to every group.

The counter voltage signal lines CL each of which is provided in commonwith respect to respective pixel regions arranged in parallel in the xdirection have right-side end portions thereof in the drawing connectedin common and the connection line is extended over the sealing member SLand the extended end constitutes a terminal CTM. A voltage which becomesthe reference with respect to the video signals is supplied from thisterminal CTM.

With respect to the above-mentioned respective gate signals lines GL,these gate signal lines GL is sequentially selected one by one inresponse to the video signal from the vertical scanning circuit V.

Further, the liquid crystal display device is configured such that thevideo signals are supplied to respective drain signal lines DL from thevideo signal driving circuit He in accordance with the selection timingof the gate signal lines GL.

<<Constitution of Pixels>>

FIG. 3 is a plan view showing the constitution of the pixel region andFIG. 4 is a cross-sectional view taken along a line IV—IV of FIG. 3.

On the liquid-crystal-side surface of the transparent substrate SUB1,first of all, a pair of gate signal lines GL (one gate signal line GLbeing not shown in the drawing) are formed such that the gate signallines GL are extended in the x direction and are arranged in parallel inthe y direction.

A pair of these gate signal lines GL surround the rectangular regiontogether with a pair of drain signal lines DL (one drain signal line DLbeing not shown in the drawing) as explained later and this regionconstitutes the pixel region.

Further, the counter voltage signal line CL which is arranged inparallel with the gate signal lines GL is formed in the region definedbetween respective gate signal lines GL.

On the surface of the transparent substrate SUB1 on which the gatesignal lines GL and the counter voltage signal lines CL are formed inthe above-mentioned manner, an insulation film GI which is made of SiN,for example, is formed such that the insulation film GI also covers thegate signal lines GL and the counter voltage signal lines CL.

The insulation film GI performs a function of an interlayer insulationfilm with respect to the gate signal lines GL and the counter voltagesignal lines CL in the region where the drain signal lines DL which willbe explained later are formed, performs a function of a gate insulationfilm in a region where a thin film transistor TFT which will beexplained later is formed, and performs a function of a dielectric filmin a region where a capacitive element Cstg which will be explainedlater is formed.

Then, on a surface of the insulation film GI, a semiconductor layer ASwhich is made of amorphous Si, for example, is formed such that thesemiconductor layer AS is superposed on a portion of the gate signallines GL.

The semiconductor layer AS constitutes a portion of the thin filmtransistor TFT. That is, by forming a drain electrode SD1 and a sourceelectrode SD2 on an upper surface of the semiconductor layer AS, an MIStype transistor having an inverse staggered structure which uses aportion of the gate signal line GL as a gate electrode can be formed.

Here, the drain electrode SD1 and source electrode SD2 aresimultaneously formed along with the formation of the drain signal linesDL.

That is, the drain signal line DL which is extended in the y directionis formed and a portion of the drain signal line DL is extended to anupper surface of the semiconductor layer AS so as to form the drainelectrode SD1, and the source electrode SD2 is formed in a spaced apartmanner from the drain electrode SD1 by a length of channel of the thinfilm transistor TFT.

The source electrode SD2 is slightly extended from the surface of thesemiconductor layer AS to an upper surface of the insulation film GI atthe pixel region side thus forming a contact portion for providing theconnection of the source electrode SD2 with the pixel electrode PX whichwill be explained later.

Further, on an interface between the semiconductor layer AS and thedrain electrode SD1 and the source electrode SD2, a thin film doped withimpurities of high concentration is formed and this layer functions as acontact layer.

The contact layer may be formed such that, at the time of forming thesemiconductor layer AS, an impurity layer of high concentration ispreliminarily formed, and using patterns of the drain electrode SD1 andthe source electrode SD2 formed on an upper surface of the impuritylayer as masks, the impurity layer which is exposed from the drainelectrode SD1 and the source electrode SD2 are etched.

On a surface of the transparent substrate on which the thin filmtransistor TFT, the drain signal lines DL, the drain electrodes SD1 andthe source electrodes SD2 are formed in the above-mentioned manner, acolor filter FIL is formed.

The color filter FIL has a color which is different from a color ofother neighboring pixel region in the x direction and is common with acolor of other neighboring pixel region in the y direction.

That is, the color filters FIL of a group of pixel regions which arearranged in parallel in the y direction are formed of common resinmaterial layers containing the same pigment and these color filters areseparately formed from the color filters FIL formed of resin materiallayers which are formed in common with respect to other group of pixelregions which are arranged in parallel in the y direction at both sidesof the above-mentioned group of pixel regions and contain the pigment ofdifferent color.

In this case, the color filter FIL also plays a role of a protectivefilm which prevents the deterioration of characteristics of the thinfilm transistor TFT by avoiding the direct contact between the thin filmtransistor TFT and the liquid crystal.

The pixel electrode PX is formed on an upper surface of the color filterFIL. The pixel electrode PX is constituted of a group of electrodesformed of a plurality of (two pieces in this embodiment) which areextended in the y direction and are arranged in parallel in the xdirection, for example. These respective electrodes are connected incommon at portions which are disposed close to the thin film transistorTFT and are electrically connected with the contact portion of thesource electrode SD2 of the thin film transistor TFT through a contacthole CH1 formed in the color filter FIL.

Then, on an upper surface of the color filter FIL on which the pixelelectrode PX is formed in this manner, a flattening film OC which ismade of a resin material layer, for example, is formed such that theflattening film OC also covers the pixel electrode PX.

Further, the counter electrode CT is formed on an upper surface of theflattening film OC. The counter electrode CT is constituted of a groupof a plurality of electrodes (three pieces in this embodiment) which areextended in the y direction and are arranged in parallel in the xdirection.

In a plan view, the respective counter electrodes CT are positioned suchthat the pixel electrode PX is arranged between the counter electrodeCT. That is, these counter electrodes CT are respectively arranged at anequal interval in the order of the counter electrode CT, the pixelelectrode PX, the counter electrode CT, the pixel electrode PX and thecounter electrode CT from the drain signal line DL at one side to thedrain signal line DL at the other side.

Further, the counter electrodes CT which are constituted of a group ofelectrodes in this manner are electrically connected with each other atportions thereof which are superposed on the counter voltage signal lineCL and have portions thereof electrically connected with the countervoltage signal line CL through contact holes CH2 which are formed in theflattening film OC and the color filter FIL as through holes.

Here, among a group of respective counter electrodes CT, a pair ofcounter electrodes CT which are positioned at both sides, that is, thecounter electrodes CT which are disposed adjacent to the drain signallines DL are formed such that their width is slightly larger than thewidth of other counter electrodes CT.

Such a constitution is adopted for facilitating the line of electricforce from the drain signal line DL to be terminated to the neighboringcounter electrode CT as well as for preventing the lines of electricforce from the drain signal line DL from getting over the counterelectrode CT and being terminated to the pixel electrode PX. That is,when the lines of electric force are terminated to the pixel electrodePX, this gives rise to noises.

Further, portions of the respective counter electrodes CT which areelectrically connected are superposed on portions of respective pixelelectrodes PX which are electrically connected by way of the flatteningfilm OC which constitutes a layer disposed below the respective counterelectrodes CT. Further, portions of respective pixel electrodes PX whichare electrically connected are superposed on the counter voltage signalline CL by way of the color filter FIL and the insulation film GI.Capacitive elements Cstg are formed at these respective superposedportions.

These capacitive elements Cstg have a function of storing video signalssupplied to the pixel electrodes PX, for example, for a relatively longperiod.

On the upper surface of the transparent substrate SUB1 on which thecounter electrodes CT are formed, an orientation film ORI1 is formedsuch that the orientation film ORI1 also covers the counter electrodesCT. The orientation film ORI1 is a film which directly comes intocontact with the liquid crystal and is provided for determining theinitial orientation direction of liquid crystal molecules by a rubbingformed on a surface thereof.

<<Relationship with Other Neighboring Pixels>>

FIG. 1 is a view showing a cross section of respective pixel regionsprovided with the red color filter FIL (R), the green color filter FIL(G) and the blue color filter FIL (B) which are arranged close to eachother. Although the pixel having two pixel electrodes PX and threecounter electrodes CT is shown in FIG. 4, to simplify the explanation,the pixel having one pixel electrode PX and two counter electrodes CT isshown in FIG. 1.

In FIG. 1, first of all, the red color filter FIL (R), the green colorfilter FIL (G) and the blue color filter FIL (B) are formed with theirlayer thicknesses made different from each other. As mentionedpreviously, there may be a case that the layer thicknesses of respectivecolor filters are intentionally set to different values to attain thebalance of transmittance or color purity among respective color filtersFIL or a case in which the layer thickness is not made uniform over allcolor filters FIL due to the irregularities in manufacturing these colorfilters FIL.

Accordingly, the difference in layer thicknesses of respective colorfilters FIL is reflected on the height of the flattening film OC formedon the respective color filters FIL from the surface of the transparentsubstrate SUB1. That is, the height of the flattening film OC is sethigh when the layer thickness of the color filter FIL is large and isset low when the layer thickness of the color filter FIL is small.

Although the flattening film OC is constituted of a resin film formed bycoating in this embodiment, it is difficult to make the flattening filmOC completely flat in a literal meaning of the word. For example, inreality, even when the complete flattening is requested, this leads tothe cumbersomeness of the manufacturing process.

Accordingly, with respect to the pixel having the color filter FIL oflarge layer thickness, the layer thickness of the liquid crystal (liquidcrystal gap) becomes small, while with respect to the pixel having thecolor filter FIL of small layer thickness, the layer thickness of theliquid crystal becomes large.

Here, the liquid crystal is interposed between the transparent substrateSUB1 and the transparent substrate SUB2 which is arranged to face thetransparent substrate SUB1 in an opposed manner and at least the colorfilters FIL are not formed on the liquid-crystal-side surface of thetransparent substrate SUB2.

In this manner, in the pixel region having the liquid crystal of smalllayer thickness, when it is necessary to make the liquid crystal obtainthe fixed light transmittance in such a portion, a voltage appliedbetween the pixel electrode PX and the counter electrode CT must beincreased, while in the pixel region having liquid crystal of largelayer thickness, the voltage which is applied between the pixelelectrode PX and the counter electrode CT must be decreased.

In other words, when the voltage applied between the pixel electrode PXand the counter electrode CT is set uniform, the light transmittance ofthe liquid crystal fluctuates in response to the layer thickness of thecolor filter FIL.

To cope with such a drawback, in this embodiment, when the layerthickness of the color filters FIL is decreased in the descending orderof the red color filter FIL (R), the green color filter FIL (G) and theblue color filter FIL (B), for example, the film thickness of theflattening film OC which is superposed on these respective color filtersFIL are sequentially increased.

To explain in more detail, the film thickness of the flattening film OCis set to satisfy the following formula (1);0<film thickness difference of interlayer insulation films between pixelregions<film thickness difference of color filters between pixelregions  (1) and

the relationship that as the thickness of the color filter FILcorresponding to the pixel is increased, the film thickness of theflattening film OC corresponding to the pixel is increased.

When material having the same viscosity as that of the material of aconventional flattening film is used as the material of the flatteningfilm OC, the coating is performed using spin coating. In this case, itis possible to set the film thickness to the above-mentionedrelationship by controlling the rotational speed of the spin to a propervalue. It is needless to say that a technique other than the spincoating can be used for forming the flattening film OC.

The liquid crystal display device having such a constitution can obviatethe elevation of the driving voltage caused by the attenuation of thedriving electric field due to the fact that the layer thickness of theflattening film OC is thick and also can obviate the lowering of thedriving voltage caused by the birefringence mode derived from the factthat the layer thickness of the liquid crystal is thick.

Since these advantageous effects work in a complementary manner, theirregularities of the driving voltage for driving the liquid crystal canbe suppressed.

Further, as another embodiment, the brightness irregularities can befurther suppressed by making the liquid crystal display device satisfy afollowing formula (2).¼×film thickness of color filter FIL between pixels<film thicknessdifference of flattening film OC between pixels, <¾×film thicknessdifference of color filter FIL between pixels  (2)

Further, in adopting the above-mentioned constitution, when the filmthickness of the flattening film OC is excessively large, the surfacebecomes flattened and hence, it is preferable to make the liquid crystaldevice satisfy a following formula (3).film thickness of flattening film OC< 3/2 times film thickness ofthickest color filter FIL  (3)

Further, when the film thickness of the flattening film OC isexcessively small, the stepped-portion narrowing effect is reduced andhence, it is preferable to make the liquid crystal display devicesatisfy a following formula (4).¼ times film thickness of thinnest color filter FIL<film thickness offlattening film OC< 3/2 times film thickness of thickest color filterFIL  (4)Embodiment 2

FIG. 5 is a cross-sectional view of another embodiment of a liquidcrystal display device according to the present invention andcorresponds to FIG. 1.

The constitution which differs from the constitution shown in FIG. 1 isthat respective counter electrodes CT which are positioned at both sidesof the drain signal line DL are connected such that the counterelectrodes CT also cover the drain signal lines DL.

Due to such a constitution, lines of electric force from the drainsignal lines DL which become a cause of noises are terminated to thecorresponding counter electrodes CT and hence, it is possible tosufficiently prevent the lines of electric force from being terminatedto the pixel electrodes PX arranged close to the counter electrodes CT.

Embodiment 3

FIG. 6 is a cross-sectional view of another embodiment of a liquidcrystal display device according to the present invention andcorresponds to FIG. 1.

The constitution which differs from the constitution shown in FIG. 1 isthat the counter electrodes CT are formed over the whole regions ofrespective pixel regions and are also connected with the neighboringcounter electrodes CT each other.

Here, as material of the counter electrodes CT, transparent materialsuch as ITO (Indium Tin Oxide), for example, is used.

Due to such a constitution, there is no fear of disconnection of thecounter electrodes CT and the total resistance value can be drasticallyreduced.

Embodiment 4

FIG. 7 is a cross-sectional view of another embodiment of a liquidcrystal display device according to the present invention andcorresponds to FIG. 5.

The constitution which differs from the constitution shown in FIG. 5 isthat the pixel electrodes PX are formed as layers below the flatteningfilm OC and the counter electrodes CT are formed as layers above theflattening film OC.

Also in this embodiment, respective counter electrodes CT which arepositioned at both sides of the drain signal line DL are connected witheach other such that the counter electrodes CT also cover the drainsignal lines DL.

Since stepped portions formed by the flattening film OC are smaller thanstepped portions formed by the color filters FIL, the counter electrodesCT formed on the stepped portions are formed on the flattening film OC.

Embodiment 5

FIG. 8 is a cross-sectional view of another embodiment of a liquidcrystal display device according to the present invention andcorresponds to FIG. 1.

The constitution which differs from the constitution shown in FIG. 1 isthat the pixel electrodes PX are formed as layers above the flatteningfilm OC and the counter electrodes CT are formed as layers below theflattening film OC. That is, this embodiment is characterized bychanging over the layers constituting respective electrodes.

Due to such a constitution, the same advantageous effects can beobtained.

Embodiment 6

FIG. 9 is a cross-sectional view of another embodiment of a liquidcrystal display device according to the present invention andcorresponds to FIG. 6, for example.

The constitution which differs from the constitution shown in FIG. 6 isthat spacers which define a gap between the transparent substrate SUB1and the transparent substrate SUB2 are constituted of so-called supportcolumns SUP which are formed on the liquid-crystal-side surface of thetransparent substrate SUB2 by selectively etching resin material using aphotolithography technique, for example.

To apply the present invention to the liquid crystal display device, itis necessary to accurately determine the layer thickness of the liquidcrystal. The irregularities of height of the liquid crystal can beminimized with the provision of the stoppers which are constituted ofthe support columns SUP.

As locations where these spacers are formed, the spacers are positionedsuch that distal ends thereof are brought into contact with the colorfilters FIL having the largest film thickness. The film thickness of theflattening film OC formed on the color filters FIL having the largestfilm thickness is small and hence, the irregularities of the filmthickness is small whereby the uniformity of the gap formed by thespacers can be ensured.

Although the irregularities of the height is increased when the heightof the spacers per se is increased, by bringing the spacers into contactwith the color filters FIL having the largest film thickness, the heightof the spacers can be made small so that the irregularities of theheight are reduced whereby the uniformity of the gap formed by thespacers can be ensured.

Embodiment 7

FIG. 10 is a cross-sectional view of another embodiment of a liquidcrystal display device according to the present invention andcorresponds to FIG. 9.

The constitution which differs from the constitution shown in FIG. 9 isthat the spacers constituted of the support columns SUP are formed onthe liquid-crystal-side surface of the transparent substrate SUB1.

Embodiment 8

FIG. 11 is a plan view showing another embodiment of the pixel of theliquid crystal display device according to the present invention andFIG. 12 is a cross-sectional view taken along a line XII—XII in FIG. 11.

Different from the liquid crystal display devices of the above-mentionedembodiments, in the liquid crystal display device shown in FIG. 11, thecolor filters FIL are formed on the transparent substrate SUB2 side andthe flattening film OC is formed such that the flattening film OC alsocovers the color filters FIL.

At respective pixel regions on the liquid-crystal-LC-side surface of thetransparent substrate SUB1, the pixel electrodes PX are formed on thegate insulation films GI, and the counter electrodes CT are formed on anupper surface of a laminated body which covers the pixel electrodes andconsists of a protective film PSV1 made of SiN film and a protectivefilm PSV2 made of organic material, for example.

Further, with respect to the counter electrode CT which is arrangedclose to the drain signal line DL out of these counter electrodes CT,such a counter electrode CT is formed such that the counter electrode CTcovers the drain signal line DL and is connected to the other counterelectrode CT which is arranged close to the drain signal line DL inother neighboring pixel region which is disposed close to the pixelregion of the counter electrode CT while sandwiching the drain signalline DL between the pixel region and the other neighboring pixel region.

Then, assuming the film thicknesses of respective protective films PSV1,PSV2 on the pixel electrode PX as d₃, d₂ and the film thicknesses ofrespective protective films PSV1, PSV2 on a region between the counterelectrode CT and the pixel electrode PX as d₃′, d₂′, when therelationship among these layer thicknesses satisfies a following formula(5), the influence of the film thickness d₄ of the pixel electrodes PXcan be attenuated.d ₃ ≈d ₃ ′, d ₂ <d ₂ ′<d ₂ +d ₄  (5)

Accordingly, the relationship between the layer thickness (liquidcrystal gap) d₁ of the liquid crystal on the pixel electrode PX and theliquid crystal gap d₁′ on the region between the counter electrode CTand the pixel electrode PX can be expressed by a following formula (6).d ₁≈d₁′ (here, d₁≦d₁′)  (6)

The reason that the condition d₁≦d₁′ is set is that it is difficult tomanufacture the liquid crystal display device under the condition ofd₁>d₁′ in actual manufacturing.

Due to such a constitution, the concentration of the electric field dueto the liquid crystal gap in respective pixels can be attenuated.

It is preferable that the approximation in the formulae (5), (6) isequal to or less than 100 nm.

Further, the electric field which is generated between the counterelectrode CT and the pixel electrode PX is weakened by the protectivefilms PSV1, PSV2 interposed between respective electrodes.

Due to the relationship expressed by the above-mentioned formula (5),the electric field applied to the protective films PSV1, PSV2 on thepixel electrode PX becomes smaller than the electric field applied tothe protective films PSV1, PSV2 in the region between the counterelectrode CT and the pixel electrode PX so that the electric field isliable to be applied to the liquid crystal at the gap d₁ portion.

FIG. 13( a),(b),(c) are views for showing the thickness x of theprotective film on the pixel electrode PX and the change of electricfield in the liquid crystal corresponding to the thickness x. As can beclearly understood from these drawings, corresponding to the decrease ofthe thickness x of the protective film, the electric field on the pixelelectrode PX is increased.

Accordingly, in this method which adopts the lateral electric fielddriving, it is possible to form the uniform electric field between thecounter electrode CT and the pixel electrode PX in each pixel region.

To explain the conventional constitution, the layer thickness of theprotective films are set such that d₃ ≈d₃′, d₂ d₂′ and the electricfield receives the influence of the film thickness d₄ of the pixelelectrode PX so that the relationship between the liquid crystal gap d₁on the pixel electrode PX and the liquid crystal gap d₁′ on the regionbetween the counter electrode CT and the pixel electrode PX is expressedas d₁+d₄≈d₁′.

In the liquid crystal of the birefringence mode used in the lateralelectric field driving, the wider the liquid crystal gap, the voltagefor driving the liquid crystal is lowered. Accordingly, the liquidcrystal at the liquid crystal gap d₁′ portion can be driven easily atthe low voltage compared to the liquid crystal at the liquid crystal gapd₁ portion.

Further, the shortest length X₁ between the counter electrode CT whichpasses along the surface of the protective film PSV2 and the pixelelectrode PX at the liquid crystal gap d₁ portion is longer than theshortest length X₁′ between the counter electrode CT which passes alongthe surface of the protective film PSV2 and the pixel electrode PX atthe liquid crystal gap d₁′ portion and the above-mentioned relationshipd₃≈d₃′, d₂≈d₂′ is established. Accordingly, based on an formula E=A×V/x(E: electric field, V: voltage applied to counter electrode and pixelelectrode, x: shortest length between counter electrode which passesalong surface of protective film PSV2 and pixel electrode, A: positiveproportion constant), the electric field applied to the liquid crystalgap d₁′ portion is remarkably increased compared to the electric fieldapplied to the liquid crystal gap d₁ portion so that the electric fieldof the pixel region in the vicinity of the pixel electrode PX becomesweak thus giving rise to the lowering of the light transmittance.

Embodiment 9

FIG. 14 is a cross-sectional view of the pixel at a portion of a liquidcrystal display device according to the present invention and FIG. 15 isa cross-sectional view of the pixel at another portion of the liquidcrystal display device. For example, in a liquid crystal display part ARof the liquid crystal display device shown in FIG. 16, a cross sectionof the pixel at the portion X in the drawing is shown in FIG. 14 and across section of the pixel at the portion Y in the drawing is shown inFIG. 15. Here, the cross-sectional portion of the pixel is similar tothat of FIG. 11.

To compare the constitutions described in FIG. 14 and FIG. 15, theydiffer in the film thickness of the protective film PSV1 at the portionof the liquid crystal display part AR. That is, while the film thicknessof the protective film PSV1 in FIG. 14 is set to x₃, the film thicknessof the protective film PSV1 in FIG. 15 is set to y₃ (<x₃).

In forming the protective film PSV1, the protective film PSVL is notformed uniformly over the entire region of the liquid crystal displaypart AR and this implies that there exists the irregularities of filmthickness.

Here, while the film thickness of the protective film PSV2 formed on theupper surface of the protective film PSV1 is set to x₂ in FIG. 14, thefilm thickness of the protective film PSV2 is set to y₂ (≈x₂) in FIG.15. That is, these film thicknesses are assumed to be substantiallyequal.

Here, the electric field applied to the region between the counterelectrode CT and the pixel electrode PX is increased at the thin portionof the protective film PSV1 since the liquid crystal gaps x₁, y₁ havethe relationship of x₁≈y₁ (substantially equal to the diameter of beadscontained in the liquid crystal).

Accordingly, in this embodiment, to make the electric field uniform overthe respective pixel regions, the film thicknessses of the protectivefilm PSV2 are set to x₂<y₂. This setting is made to compensate for therelationship x₃>y₃ of respective film thicknesses of the protective filmPSV1.

In view of the above, a following formula (7) is established.x ₂ +x ₃ ≈y ₂ +y ₃ , x ₃ >y ₃ , x ₂ <y ₂  (7)

In the above-mentioned respective embodiments, the pixel electrodes PXare formed as layers below the protective film PSV and the counterelectrodes CT are formed as layers above the protective film PSV.However, it is needless to say that the pixel electrodes PX and thecounter electrodes CT may be formed in a reverse manner. That is, thepixel electrodes PX are formed as layers above the protective film andthe counter electrodes CT are formed as layers below the protective filmPSV.

Embodiment 10

When the distance from the substrate SUB1 to the liquid crystal layerdiffers, the thickness of the liquid crystal layer differs as shown inFIG. 17 as an example. In the lateral electric field, the drivingvoltage depends on the thickness of the liquid crystal layer. That is,the thicker the liquid crystal layer, the same brightness can beobtained with the lower voltage. Assuming that the distance between theelectrodes is all equal in FIG. 17, the pixel in the region X assumesthe higher driving voltage than the pixel in the region Y. Thisphenomenon is explained in conjunction with FIG. 22. In FIG. 22, the B-Vcurves are shown, wherein the voltage V is taken on the axis ofabscissas and the brightness B is taken on an axis of ordinates. Aindicates the B-V curve in the region X in FIG. 17 and B indicates theB-V curve in the region Y in FIG. 17. The curve A takes the gentler B-Vcurve than the curve B. Accordingly, these curves A, B differ in thegray scale displayed with respect to a certain voltage.

Accordingly, in this embodiment, as shown in FIG. 17, the distancebetween the electrodes is configured to have the particularconstitution. The distance from the substrate SUB1 to the counterelectrode CT at the pixel corresponding to the region X is longer thansuch a distance at the pixel corresponding to the region Y. In FIG. 17,the distance from the substrate SUB1 to the counter electrode CT assumesthe relationship d10>d20. Although a plurality of counter electrodes CTmay be provided for each pixel, in FIG. 17, two counter electrodes CTare provided for each pixel. Assuming the distance between the counterelectrodes CT at the pixel corresponding to the region X as L3 and sucha distance at the pixel corresponding to the region Y as L6, therelationship L6>L3 is satisfied. That is, this embodiment ischaracterized in that the distance between the counter electrodes CT atthe pixel corresponding to the region X is shorter than the distancebetween the counter electrodes CT at the pixel corresponding to theregion Y.

Due to such a constitution, it is possible to make the intensities ofelectric field which are respectively formed in the region X and theregion Y when the equal voltage is applied to become more uniform sothat it is possible to make the inclinations of the B-V curves of bothregions close to each other. Accordingly, the displacement of the grayscale can be reduced.

Further, assume the distance between the pixel electrode PX and thecounter electrode CT at the pixel corresponding to the region X as L1and L2 and the distance between the pixel electrode PX and the counterelectrode CT at the pixel corresponding to the region Y as L4 and L5.Here, by making these distances satisfy the relationship L4, L6>L1, L2or at least one of the relationships L4>L1 or L4>L2 and L5>L1 or L5>L2,it is possible to make the intensities of electric field respectivelygenerated in the region X and the region Y when the equal voltagesapplied to become more uniform so that the inclinations of the B-Vcurves of both regions can be made closer to each other. Accordingly,the displacement of the gray scale can be reduced.

In FIG. 17, as an example, the protective film PSV1 is made of aninorganic film and the protective film PSV2 is made of an organic film,for example. In FIG. 17, the counter electrodes CT are arranged over thevideo signal lines DL by way of the organic films PSV2. Accordingly,while suppressing the parasitic capacitance between the video signallines DL and the counter electrodes CT, it is possible to shield theelectric field leaked from the video signal lines DL. To sufficientlyobtain only the leaked electric field shielding effect by lowering theparasitic capacitance, it is preferable that the protective film PSV2has some thickness. From this point of view, it is preferable that theprotective film PSV2 is made of the organic film. However, the organicfilm has a serious drawback that the film thickness irregularitiesintrinsic to a coating device is liable to be generated. However, byadopting the concept of this embodiment, the influence of the differenceof the film thickness to the B-V curves can be obviated so that it ispossible to sufficiently obtain only the leaked electric field shieldingeffect.

Embodiment 11

FIG. 18 shows another constitutional example which can realize theimprovement effect obtained by the embodiment 10. This embodimentdiffers from the embodiment 10 with respect to a point that the numberof counter electrodes CT and the number of pixel electrodes PX areincreased as shown in FIG. 17. This embodiment also differs from theembodiment 10 with respect to a point that both of the counterelectrodes CT and the pixel electrodes PX are formed over the protectivefilm PSV2. Constitutions other than the above-mentioned constitutionsare as same as the corresponding constitutions in FIG. 17 and bringabout the similar advantageous effect as the advantageous effectsobtained by the corresponding constitutions in FIG. 17.

The distances from the substrate SUB1 to the pixel electrodes PX are setto d30>d31, wherein the distance at the region X is made larger than thedistance at the region Y. Here, the distance between the pixelelectrodes PX is set to satisfy the relationship L8>L7 wherein L7indicates the distance at the region X and L8 indicates the distance atthe region Y. Accordingly, due to such a constitution, in the samemanner as the embodiment 10, it is possible to make the intensities ofelectric field which are respectively formed in the region X and theregion Y when the equal voltage is applied to become more uniform sothat the inclinations of the B-V curves of both regions can be madecloser to each other. Accordingly, the displacement of the gray scalecan be reduced.

Embodiment 12

The reduction of the displacement of the gray scale which has beenexplained in conjunction with the embodiment 10 is also effective withrespect to the constitution which provides the difference in thethickness of the liquid crystal layer between the neighboring pixels.

FIG. 19 shows the constitution in which the thickness of the liquidcrystal layer differs between the neighboring pixels. As the protectivefilm PSV2 shown in FIG. 17, color filters FIL are provided. FIG. 19shows the cross-sectional structure of a plurality of pixels in thedirection that the gate signal lines GL are extended. In the drawing,the color of the color filter FIL assumes any one of values R, G, B forevery pixel thus constituting the three primary colors. The boundariesof the color filters are positioned on the drain lines DL. In the liquidcrystal display device, it is necessary to realize the given color.Accordingly, it is difficult to make the color filters have thecompletely equal thickness among colors. Accordingly, as shown in FIG.19, the liquid crystal display device is configured such that thedistance from the substrate SUB1 to the liquid crystal layer differsevery pixel corresponding to the color filter FIL so that the thicknessof the liquid crystal layer also differs every pixel.

To reduce the displacement of the gray scale using such a structure, itis advantageous to adopt at least one of following means.

(1) With respect to respective pixels, the longer the distance from thesurface of the substrate SUB1 to the counter electrode CT, the distancebetween the counter electrodes CT is made shorter.

(2) With respect to respective pixels, the longer the distance from thesurface of the substrate SUB1 to the counter electrode CT, distancebetween the counter electrode CT and the pixel electrode PX is madeshorter.

This embodiment can reduce the displacement of the gray scale byadopting both of the above-mentioned means (1), (2).

The order of the film thickness of R, G, B in this embodiment is set foran explanation purpose and it is not always necessary to adopt thisorder. That is, the order can be suitably determined in conformity withthe characteristics of materials of respective colors used for formingthe color filters FIL. The essential point is that at least one of theabove-mentioned means (1) or (2) is satisfied.

Embodiment 13

FIG. 20 is a constitutional example in which the counter electrodes CTand the pixel electrodes PX in FIG. 19 are arranged over the colorfilters FIL. This constitution can also realize the reduction of thedisplacement of the gray scale by adopting at least one of the means(1), (2) of the embodiment 12. In this embodiment, both means (1) (2)are adopted thus enhancing the reduction of the displacement of the grayscale.

Embodiment 14

FIG. 21 shows a schematic cross-sectional structure of a plurality ofneighboring pixels in this embodiment. The difference between thestructure shown in FIG. 21 and the structure shown in FIG. 19 lies inthat an overcoat OC is formed over the color filters FIL. Differencealso lies in that the counter electrodes CT are formed over the overcoatOC and the pixel electrodes PX are arranged below the overcoat OC.

The constitution of this embodiment also can realize the reduction ofthe displacement of the gray scale by adopting at least one of means(1), (2) of the embodiment 12.

Further, this embodiment is also characterized by the relationship ofthe film thickness of the overcoat OC with respect to the color filtersFIL. That is, the overcoat OC is thin at the pixel having the thickcolor filter FIL and the overcoat OC is thick at the pixel having thethin color filter FIL. Due to such a constitution, the difference ofthickness of liquid crystal layer among pixels having different colorscan be reduced more compared to the state in which the overcoat OC isnot provided. Due to such a constitution, the displacement of the grayscale can be reduced.

The overcoat OC having the relationship shown in FIG. 21 as an examplecan be realized by coating overcoat material in a liquid form whoseviscosity is suitably determined on the color filters FIL, then leavingthe overcoat material for several tens of seconds and, thereafter,heating the overcoat material OC together with the substrate SUB1.

In this embodiment, by adopting the structural feature which can reducethe difference of thickness of the liquid crystal layer and both ofmeans (1), (2) of the embodiment 12, the displacement of the gray scalecan be further reduced.

Embodiment 15

FIG. 22 corresponds to FIG. 21. The constitution shown in FIG. 22differs from the constitution shown in FIG. 21 with respect to a pointthat the pixel electrodes PX are also formed over the overcoat OC.

The constitution of this embodiment also can reduce the displacement ofthe gray scale by adopting at least one of means (1), (2) of theembodiment 12.

The above-mentioned respective embodiments may be used in a single formor in combination. This is because that the advantageous effects ofrespective embodiments can be obtained in a single form or incombination.

As can be clearly understood from the above description, the liquidcrystal display device according to the present invention can enhancethe display quality.

1. A liquid crystal display device comprising: first and secondsubstrates with a liquid crystal layer sandwiched in-between, aplurality of electrodes formed on the first substrate, a firstprotective film formed on the first substrate and the electrodes, asecond protective film formed on the first protective film, wherein therelationship among the thicknesses d₃, d₂ of the first protective filmand the second protective film above the electrodes of a thickness d₄,the thicknesses d₃′, d₂′ of the first protective film and the secondprotective film on the first substrate without the electrodes formedunderneath satisfies a formulad ₃ ≈d ₃ ′, d ₂ <d ₂ ′<d ₂ +d ₄, and the relationship between thethickness d₁ of the liquid crystal layer on the region which theelectrodes are arranged and the thickness d₁′ of the liquid crystallayer of the region without the electrodes being arranged satisfies aformulad₁≦d₁′.
 2. A liquid crystal display device comprising: first and secondsubstrates with a liquid crystal layer sandwiched in-between a displayregion which displays an image and is arranged on the first and secondsubstrates, a plurality of pixel regions arranged in the display region,a plurality of electrodes formed on the first substrate, a firstprotective film formed on the first substrate and the electrodes, asecond protective film formed on the first protective film, in twoselected pixel regions, assuming the thickness of the first protectivefilm in one pixel region as x₃, the thickness of the second protectivefilm in said one pixel region as x₂, the thickness of the firstprotective film in another pixel region as y₃ and the thickness of thesecond protective film in said another pixel region as y₂, a formula isestablishedx ₂ +x ₃ ≈y ₂ +y ₃, (where x ₃ >y ₃ and x ₂ <y ₂).